This invention relates to a method for transferring semitrailers from one point to another as, for example, in the loading and unloading of railway flat cars or between dock and storage in an industrial plant or other controlled access area. In particular, the invention is directed to a method and apparatus for transferring semitrailers using automatically guided, power-driven, fifth wheel stanchions. The invention is also directed to a power driven stanchion that is capable of manual and/or automatic operation.
A usual practice in a system for loading semitrailers on flat cars is to use a specially devised tractor to position the semitrailers, one trailer at a time, on a flat car of a train or, alternatively, to pick the trailers up bodily with a crane. One such system is disclosed in U.S. Pat. No. 2,903,977 in which the tractor has a fifth wheel coupling that can be elevated for coupling to a semitrailer to be loaded on a train, and after loading, the tractor support of a semitrailer is replaced by a pedestal for supporting and securing the semitrailer during its journey. My copending Patent Application No. 853,561, filed Apr. 18, 1986, discloses another system using a power driven stanchion, which is provided for each semitrailer and remains coupled thereto for use in unloading its associated semitrailer at its destination. In each of these systems, the semitrailers can be loaded or unloaded only one at a time. This is time consuming and labor intensive.